Dependence Of Small-signal Gain Research Articles

Temperature dependence of Alexandrite effective emission cross section and small signal gain over the 25-450 °C range

We present detailed measurements of effective emission cross section spectra of the Alexandrite gain medium in the 25-450 °C temperature range and provide analytic formulas that can be used to match the measured spectra. The measurement results have been used to investigate the wavelength and temperature dependence of small signal gain, as well as gain bandwidth relevant for ultrafast pulse generation/amplification. We show that the estimated laser performance based on the measured spectroscopic data provides a good fit to the results in the literature. We further discuss the need for a detailed measurement of excited-state absorption cross section in future studies.

Pressure dependence of small signal gain and saturation intensity of a gold-vapor laser using various buffer gases in gain medium

A pair of gold-vapor laser (627.8 nm) in an oscillator–amplifier configuration was used to investigate the small signal gain, g 0, and saturation intensity, I s, as amplifying parameters, versus pressure at various types of buffer gas. It was shown that the small signal gain decreases and saturation intensity increases linearly with increasing the pressure. Moreover, the values of these parameters are different using various gas mixtures in gain medium. Both parameters were estimated to be more at helium buffer gas atmosphere than that of neon or their mixed ones.

Numerical investigation of a fast-axial-flow CW CO 2 laser

This paper presents the results of the calculation of the parameters of the active medium of a fast-axial-flow CO 2 laser using numerical methods in the framework of a one-dimensional approximation of the set of continuity equations, Bernoulli equation, equation of gas state, energy equation and multi-temperature rate equations with regard to diffusion for the gas flow in the cylindrical discharge tube. The spatial distribution of the small-signal gain and gas temperature along the gas flow direction have been calculated for a given set of initial conditions, namely, gas flow velocity, gas pressure and the tube diameter. In addition, the dependence of small-signal gain, the asymmetric stretch vibrational temperature of CO 2 ( T 3) and the gas temperature on the discharge current were studied.

Coupled mode competition in unstable resonators using the exact cavity equations of motion with dynamic gain

The dynamic coupled mode (DCM) method has been applied to study the transverse mode competition in optical resonators. In this work a differential equation for the homogeneously saturating dynamic gain is included in the original dynamic coupled mode method, thus increasing its physical resemblance and allowing the retrieval of gain temporal evolution at every point within the lasing medium. This new model provides a realistic temporal evolution of the mode competition and gain saturation within the resonator, which can give further information on spatial coherence properties. The new general formulation does not assume that lasing medium fills the optical cavity and is suitable for modelling the dependence of small-signal gain and power gain on the transverse and longitudinal coordinates. The application of the method to a typical CO2 unstable confocal resonator is fully described; results and their connection to relevant physical properties of gas lasers, such as spiking and relaxation oscillations, are discussed. Results of the numerical implementation of the DCM method with dynamic gain are in very good agreement with experimental measurements reported previously.

Development of High Pressure E-beam Controlled CO<SUB>2</SUB> Laser

High pressure E-beam controlled CO2 laser has been constructed and its performance characteristics has been investigated. Uniform glow discharge of arbitraly gas mixture of CO2, N2 and He is easily obtained up to 15 atomospheric pressure. Small signal gain is 4%/cm at electrical energy input of 150J/latm. The pressure dependence of small signal gain shows the gain overlapping of vibrational-rotational levels.

Characteristics of a gallium-arsenide travelling-wave amplifier with Schottky-barrier contacts

Experimental results of the dependence of small-signal gain on bias voltages, applied to Schottky-barrier contacts which are r.f. input and output terminals of a gallium-arsenide travelling-wave amplifier are reported. In the optimum bias condition, a maximum net gain of 10 dB at 6.6 GHz in d.c. operation has been observed.